Rotary expansible chamber devices – Moving cylinder – Rotating
Reexamination Certificate
2002-09-04
2004-02-24
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Moving cylinder
Rotating
Reexamination Certificate
active
06695603
ABSTRACT:
BRIEF DESCRIPTION OF THE INVENTION
The invention relates to a toothed rotor set for a pump or an engine consisting of a rotating outer rotor. There is an inner rotor inside the outer rotor, which has bearing (oil) pockets for planetary gears. The toothed rotor set is similar to a ring pump with toothed execution. The function and procedure of the toothed rotor set correspond to the function and procedure of a toothed ring pump.
In toothed ring pumps, the pressure chamber is not separated from the suction chamber by a sickle shaped filling piece. Instead, a special shaping of the teeth—based on the trochoidal teeth system—ensures the sealing between the toothed ring and the outer toothed-pinion. The ring with inner teeth has one tooth more than the pinion, so that if the teeth are shaped properly, the tooth crests touch the exact tooth contact point. To ensure rolling, there must be a crest clearance between the tooth crest of the outer rotor and the tooth crest of the inner rotor. The disadvantage in the case of the ringed pump is that this crest clearance causes inner leakages that in turn lead to bad volumetric performance. In fact, at low speeds, it is not possible to build high pressures for this reason.
In comparison to a ringed pump, it is more advantageous to have a pump conforming to the principle of DE A 196 46 359. The pump is designed as a toothed rotor set consisting of a bearing ring with an inner tooth system and a gear placed eccentrically inside it, having outer teeth. The inner tooth system is formed by rollers that can rotate in the bearing ring, and it has one tooth more than the outer tooth system. A fine teeth system with an essentially smaller module is superimposed on the outer teeth of the gear.
Each roller has a fine tooth system on its circumference with the same module with which the teeth of the gear interlock.
The function of the toothed rotor set is that a drive momentum impacts against the inner rotor through a drive shaft, and makes it rotate. The toothed inner rotor transfers a force to the planetary gear, which on one hand manifests itself as an impact through the center of the planetary gear, and on the other, as a radial force that creates a torque for the planetary gear. The impact on the bearing ring causes it to rotate.
The known toothed rotor set has the disadvantage that a large number of planetary gears must be used to enable the function. And the use of a large number of planetary gears results in relatively higher incidence of friction, which the torque of the drive shaft connected to the inner teeth system must overcome. Another disadvantage of known toothed rotor sets is that when the inner rotor rotates, lubrication oil (grease) rotating in the same direction flows into the gaps between the teeth of the planetary gear from the pressure side to the suction side, and this flow lowers the efficiency of the pump.
The disadvantages of the latest technology status highlight the task of creating a toothed rotor set designed in such a way that for the same model size, a lesser number of planetary gears is used to reduce the incidence of friction. The task of the invention is also to create a toothed rotor set that offers larger pumping volumes and higher efficiency at comparable model sizes, than the known toothed rotor sets.
SUMMARY OF THE INVENTION
The problem is solved according the invention, by a toothed rotor set for a pump or an engine consisting of a rotating outer rotor with an approximately star shaped bore. The bore has a fine inner teeth system and an inner rotor aligned eccentrically inside it, having oil pockets for planetary gears.
The planetary gears have a fine teeth system with which they roll in the fine teeth system of the outer rotor. The outer teeth system has one tooth less than the inner teeth system of the outer rotor. The advantage of a toothed rotor system designed in this manner is that in comparison to known toothed rotor sets from the latest status of technology, the toothed rotor set conforming to the invention can be driven by a smaller number of planetary gears. This is because for the same model size, a smaller number of planetary gears are used than in the known toothed rotor sets conforming to the latest technology status. Smaller number of planetary gears further means smaller friction areas for example, between the planetary gears and the oil pockets of the inner rotor as well as between the teeth of the planetary gear and the teeth of the outer rotor. Less friction means that a pump or engine with a toothed rotor set conforming to the invention has greater efficiency than the pump or engine with the known toothed rotor set conforming to the latest technology status, because lesser torque must be used to overcome the friction in the system. From the perspective of design, the toothed rotor set enables a higher pumping volume than the known toothed rotor set conforming to the latest technology status.
In addition, the toothed rotor set conforming to the invention has a higher efficiency because when the inner rotor rotates in the clockwise direction, the planetary gears rotate in the anti-clockwise direction leading to an additional flow of lubricating oil in the gaps between the teeth of the planetary gears from the suction side to the pressure side.
A further problem of the fine teeth system is that the forces and moments that come into play are not optimally accepted by the involute teeth systems used thus far in the toothed rotor sets conforming to the traditional genre. In particular, there is the problem that the known teeth systems do not transfer the impact and radial forces in the linear direction without a high degree of surface friction.
The thus far known teeth systems are suitable only for transferring large radial forces and not for transferring large impact forces that travel through the center of the planetary gears.
A disadvantage of the genus-building toothed rotor set is that it does not ensure clean rolling under all operational conditions, without interlocking disturbances. The movement of the planetary gears relative to the bearing ring eventually comes to a standstill.
In this condition, when the planetary gear is almost stationary and simultaneously, a large force is transferred, there is the real danger that the lubrication film between the tooth crest of the planetary gear and the bearing ring may burst, leading to stoppage of the oil flow. The result is fixed body contact through the loss of lubrication oil in the crevices. Favorable hydrodynamic lubrication conditions are no longer there, and these have been replaced by conditions of hybrid friction, which, in the worst scenario case can end in jamming. In case of mixed friction or jamming, erosion takes place, thus reducing the life of the toothed rotor set.
In an advantageous design of the toothed rotor set conforming to the invention therefore, at least one section of the inner and/or outer fine teeth has an arched component. The advantage of a toothed rotor set designed in this manner is that due to the arched component, rolling friction takes place, but no sliding friction is possible, so that erosion of the teeth is minimized.
The convex shaped tooth crest of the fine-toothed planetary gear and the concave shaped tips of the fine-toothed outer rotor ensure that there is surface contact but no linear contact. The Hertz pressing is reduced considerably through this roller pair.
By incorporating a flank clearance between the teeth of the planetary gear and the gaps in the teeth of the outer rotor, it is ensured that transmission of the larger impact forces takes place only over the tooth crest and the tooth tips. This way it is ensured that no large wedging forces impact on the flanks of the tooth system. Such impacts can destroy the flank surfaces. Additionally, the lubrication oil from the gaps between the teeth can flow out through the flank clearance, as otherwise, it might lead to squeezed oil, which can lead to the formation of high pressure.
In an advantageous design of the toothed rotor set conforming to the inve
Bachmann Josef
Ernst Eberhard
GKN Sinter Metals GmbH
Vrablik John J.
Woodcock & Washburn LLP
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